Welcome! Grats on your sobriety. I think with sobriety at times comes this crystal clear clarity when you see others using--how selfish they are, how rude and insensitive they are.
Talk to your parents. Tell them what you've said to us. You don't have to be combative or defensive, just let them know what's going on. Tell them that she is abusing drugs, doing something illegal, putting your sobriety at risk. You don't have to get into the whole, "how can you tell me I have to stay clean when you let her do drugs here," just iterate how this makes you feel and what the risks are. Beg them. Plead with them. They should know. If you've told them before, tell them again. Be a squeaky wheel.
And go to all the meetings you can is my suggestion.
Have you thought about calling the police if she brings drugs into the house again? I don't know, just a thought.